Retrievable pressure recording bomb and choke



United States Patent.Y

RETRIEVABLE PRESSURE RECORDING BOMB AND CHOKE Douglass M. Stewart, Houston, Tex., assignor, by mesne assignments, to Esso Research and Engineering Company, Elizabeth, N. J., a corporation of Delaware Application September 20, 1954, Serial No. 457,038

4 Claims. (Cl. 73151) This invention relates to the production of oil. More particularly, this invention relates to a retrievable instrument Which contains therein a choke or restricting means and also contains therein a pressure recorder. The pressure recorded lon the pressure recorder is used to determine whether the choke or restricting means is functioning properly.

In obtaining fluids such as oil from a formation producing under its own pressure it is common practice in the oil industry to include a choke or restricting means for the purpose of regulating the rate of flow of the liquid through the drill stem. The size of the orice within the choke is determined by the characteristics of the liuid being produced and also depends upon the pressure of the producing formation. In previously utilized liquid producing systems a retrievable choke has been included in -the system. Also utilized in previous oil producing Vsystems is a pressure recording bomb which is retrievable and indicates the pressure of the producing formation. However, I am the first to utilize a retrievable instrument which includes therein both a choke and a pressure recording bomb with the pressure recording bomb giving an indication of whether the choke is functioning properly. My new device offers a number of advantages over present methods of making drill stem tests. It affords an opportunity for pulling out a plugged choke and installing a clean choke. By the provision of a removable choke within my new instrument, when some idea of the flowing characteristics of a well have been obtained, if deemed necessary, the choke size might be changed to afford better flow control. By the provision of the retrievable pressure bomb, all that is necessary is that the retrievable instrument be brought to the surface, for example, by means of a wire line and the record of the pressure bomb inspected. This can be done without the necessity of pulling the entire drill string and test tool. By observing the pressure-time traverse recovered from the recording pressure bomb the operator at the surface can easily determine whether a choke has been plugged or is operating properly and from the record can also determine subsurface events leading up to the plugging of the choke. Plugged chokes, faulty pressure recorders and unsatisfactory tests due to improper choke sizes are ditliculties experienced frequently during drill stem tests.

Briefly described, my invention consists of a retrievable housing adapted to be introduced into a tubing string. A specially constructed tubing sub is provided in the tubing string, said tubing sub being provided with means for confining the retrievable housing therein. A removable choke and a removable pressure recorder is disposed within the housing. Fluid ports are also provided in the housing, said ports being located so as to cause uids from a subsurface formation to flow through the removable choke and also `apply pressure against the pressure recorder.

Various uobjects of the present invention will be apparent from the following description taken in connection with the accompanying drawings, in which:

Fig. 1 is a side elevational View partly in section show- Iing the drill string sub included in the drill string for the purpose of carrying out my invention and also showing my new retrievable choke and pressure recording bomb instrument;

Fig. 2 is a continuation of Fig. 1 showing an example of a drill stem tester which might be utilized with my new retrievable choke and pressure recording means; and

Fig. 3 is a side elevational sectional view of an example of a pressure recording bomb which may be utilized in my new invention.

Referring more particularly to the drawings, numeral 4 represents a borehole which traverses a producing formation. As shown in Fig. 2, a drill stem tester is included in the drill string for the purpose of collecting the fluids which are forced out of the producing formation by the formation pressure, said fluids rising up into the drill stem to a height depending upon the pressure within the formati-on. The drill stem tester might be any drill stem tester commonly utilized for taking drill stern tests, The particular drill stern tested shown in Fig. 2 is similar to that described in the patent to E. P. Halliburton, No. 2,092,062. When it is `desired to take a drill stem test, the drill stem is rotated to the right looking downwardly from the surface of the borehole causing pin 5 to move in slot 6. By such a movement the head 7 which is connected to a tube 8 is made to contact the head 9 of valve member 10. Valve member 10 will then be moved downwardly against the force of coil spring 11, permitting fluids to run through fluid openings 12 and on up through fluid passageways 13 and 14 and up the drill stem to a height depending upon the pressure. Packer 15 is utilized to prevent the fluid mud which fills the annulus around the outside of the apparatus from entering the apparatus when the valve is opened.

Connected to the drill stem tester by means of a drill collar 16 is my new drill stem sub 17 which has present therein a packing seating means 18, such as a shoulder, and a latch hold-down means 19. The retrievable pressure recording bomb and choke instrument is -an elongated cylindrical mandrel 20 containing a hold-down latch 21, a retrieving head 22 and a hold-up latch 23. Fluid by-pass ports 24 are also provided in the mandrel. The mandrel 20 is provided with a first chamber 20a and a second chamber 2011 above the rst chamber 20a. The instrument has disposed therein in chamber 20a a recording pressure bomb 25, a choke 26 which interconnects uidly chambers 20a and 20h and a choke cage 27. If desired, an instrument for collecting liquid samples can be placed in the section of the retrievable pressure recording bomb and choke instrument labeled S in Fig. l.

Disposed about the retrievable instrument 20 is a packing seating means 40. This packing can be made of `an O ring seal or in the alternative might be made of an inverted rubber type cup. The packing means 40 fits tightly against the shoulder 18 when the removable instrument is introduced or dropped into the drill string. The fluid tight contact between the packing means 40 and the shoulder 18 prevents uids from entering the drill string section 28 without first passing through the choke 26. Choke 26 is removable and is screwed into the choke cage 27. It is to be understood that a choke having `an orifice of any size, depending upon which is the most expedient size, can be inserted in choke cage 27. If it is subsequently determined that the initial choke is not suitable, a choke of a different sized orifice may be substituted therefor.

In Fig. 3 there is shown in sectional elevational view an example of the type of pressure recording bomb which might be used in my invention. The bomb contains a suitable spring driven clock 30 which rotates a chart drum 31 by means of a shaft 32, a suitable chart maintained within drum 31, as shown, and a stylus 33 records variations in pressure due to a change of position of spring 34 actuated by piston 35 which in turn is actuated by the formation pressure in area 36 transmitted through ports 37. Ports (not shown) are provided in mandrel 20 for transmitting the lluid pressure into the interior of the mandrel 20 and through ports 37.

In operation my new instrument is lowered down the drill string on a wire line to the drill pipe sub 17 (Fig. l). When it is ladjacent the drill pipe sub 17, hold-down latch 21 is moved inwardly against the force of a resilient spring by latch stop 19. The hold-down latch 21 is a spring-biased latch which is moved inwardly when a wire line is used to pull up the retrieving head 22. The hold-down latch is of the type shown in the patent to J. C. Stokes, No. 2,528,981. The provision of the holddown assembly prevents the retrievable instrument from being pushed up the drill strig by the pressure of the fluids. When the retrievable instrument has been properly seated, the drill string is turned, the head 7 is permitted to push valve 10 downwardly thereby permitting iluids to go up the drill string through the fluid passageways 12, 13 and 14 (see Fig. 2). The uid path includes the space between the retrievable instrument and the drill stem sub 17 and fluid flows through the orice of choke 26 (as shown by the arrows in Fig. 1). At the same time the pressure of the lluids is recorded by means of pressure recorder 25. When it is desired to ascertain whether the choke is functioning properly the operator retrieves the retrievable choke and pressure recording bomb instrument and inspects the record of the pressure. The mandrel is threaded at 41 to permit the removal of the recording bomb. By an inspection of the record the operator can determine whether the choke 26 is functioning properly and, if not, take steps to remove the removable choke 26 and replace the choke with another choke.

Having described the invention, it is claimed:

1. For use with a sub-surface formation fluid tester attached to a string of tubing and adapted to be lowered in a borehole to the proximity of a subsurface formation to be tested: a wire line retrievable mandrel adapted to be lowered into said tubing; a removable choke disposed within said mandrel and coaxial therewith; a pressure recorder within said mandrel; and means for causing any well fluid to flow through said removable choke, said choke having an open bore and being disposed in said mandrel above said recorder with the pressure recorded on said pressure recorder indicating whether said removable choke is functioning properly on ow of said well fluid trst against the pressure recorder and then through the choke.

2. For use with a subsurface formation fluid testerz a drill pipe sub having a latch stop and a packing shoulder; a wire line retrievable housing adapted to be introduced into said drill pipe sub; a hold-down latch in said housing, said hold-down latch being adapted to engage said latch stop; a shoulder about said retrievable housing adapted to engage the packing shoulder in the drill pipe sub; a packing seal disposed about the housing, the

outside periphery of said packing seal being adapted to seat within the inside periphery of said packing shoulder in fluid tight engagement; a removable choke disposed Within said housing and coaxial therewith; a pressure recorder within said housing; and means for causing Iany well uid under pressure to flow through said removable choke, said choke having an open bore and being disposed in said housing above said recorder, with the tlow of said well fluid being first against the pressure recorder and then through the choke whereby pressure recorded on said pressure recorder indicates whether said removable choke is functioning properly.

3. For use with a subsurface formation Huid tester: a -drill pipe sub having la packing shoulder; a wire line retrievable housing adapted to be introduced into said drill pipe sub; a packing seal disposed about the housing, said packing seal being adapted to seat against said packing shoulder in fluid tight engagement; a removable choke and a removable pressure recorder disposed within said housing; said choke having 'an open bore and being disposed in said housing above said recorder; and means for causing any fluid under pressure from said subsurface formation to flow rst against said pressure recorder and then through the removable choke whereby the pressure recorded on said pressure recorder indicates whether said removable choke is functioning properly.

4. For use with a subsurface formation fluid tester: a drill pipe sub having a latch stop and a packing shoulder; a wire line retrievable housing ladapted to be introduced into said drill pipe sub, said housing having a first lower chamber and a second upper chamber; removable uid flow regulating means having a full opening bore interconnecting said chambers; 'a hold-down latch in said housing, said hold-down latch being adapted to engage said latch stop; a shoulder about said retrievable housing adapted to engage the packing shoulder in the drill pipe sub; a packing seal disposed about the housing, the outside periphery of said packing seal being adapted to seat within the inside periphery of said packing shoulder in fluid tight engagement; a pressure recorder disposed within the lower of said chambers; and means for causing any uid under pressure to flow first against said pressure recorder and then through said lluid flow regulating means, whereby pressure recorded on said pressure recorder indicates whether said uid How regulating means is functioning properly.

References Cited in the file of this patent UNITED STATES PATENTS 2,092,062 Halliburton Sept. 7, 1937 2,161,233 ONeill June 6, 1939 2,178,540 McNeese et al. Nov. 7, 1939 2,189,919 Moore Feb. 13, 1940 2,213,950 Crites Sept. 10, 1940 2,528,981 Stokes Nov. 7, 1950 2,598,932 Natho June 3, 1952 2,604,169 Miller July 22, 1952 2,702,474 Johnston Feb. 22, 1955 

